SPSS 15 for Windows

Notes:

If you have a previous version of SPSS, uninstall it before installing
SPSS 15.
Before you uninstall the old version, move any files you wish to
keep from the SPSS directory into another directory. This recommendation is intended for data, syntax,
output, scripting files, chart templates, etc and not to SPSS system
files.

Make sure your computer is connected to the internet during the installation.